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Discussion Starter #1
My MR2 has developed a disturbing problem with the headlights. While driving along at night the headlights and dashlights will completely go out. If I thump the side of the instrument pod the lights will come back on most of the time. Thumping the steering wheel does not help. Turning the lights off and then on does not fix the problem. At other times when the lights are working fine, if I go to high beams the headlights along with the dash lights go out but if I use the high beam flash switch they work fine. And yet other times I'll lose the dash lights but the headlights will stay on but a thump of the instrument pod brings them back.

Obviously there is a loose connection or bad spot in a switch somewhere. Adjusting the brightness switch on the dash has no affect on the dash lights when they have gone out so that rheostat seems to be okay. That leaves the headlight switch or the dimmer switch. Though when the headlights go out the headlights do not retract so the sytem is still engergized. The headlight switch is housed in the instrument pod while the dimmer switch is in the steering column.

My question is: which is most likely to be the culprit, the dimmer switch or the main headlight switch? I can get to both and remove them to clean up the contacts but the headlight switch is going to be a whole lot easier to access. My first instinct is to suspece the dimmer switch though, but the thump to the instrument pod that makes things come back on would only affect the headlight switch. I'm baffled.

TIA!
 

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Have a schematic on that circuit you can send over? I'd be curious on some things.
Where does the headlights get power from?
Where does dash light power come from?
Where does the headlight retraction get power from?
If power comes from the same place or fuse for all three, problem sounds like it's headlight switch related.
If the retraction system gets power from another fuse, problem can be on the input side of the headlight switch.
 

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Discussion Starter #3
I have the wiring diagrams at home in the shop manual.

I do know the headlights and headlight retractors are on different circuits and different fuses. In short, you can turn the headlights on but if the retractor fuse is blown they will not rise up. They can be brought up manually with knobs in the front trunk for just such emergency situations.

Tonight I'm going to pull the headlight switch and give it a once over. It's probably a sealed unit but I gotta try. The last time the headlights went out I was just rounding a curve and they went out just as the lights caught a deer crossing sign! Of course I was in an rural area with no streetlights so it was quite disturbing since it was so hard to tell if I was even still on the road!
 

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Boldly procrastrinating
66 El Camino 57 Chevy pickup 2004 Tahoe
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kinda got that bad ground smell around it. Look under the dash/pod for a ground being loose.
 

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Sounds like your car is possessed. I recommend you contact a Catholic priest to have it exorcized. Don’t forget to pay him you don’t want it to be repossessed. If you’re under 12 be sure to have adult supervision. :D
 

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Discussion Starter #9
Originally posted by John_Muha:
How do the dash lights get power?
I don't know exactly. They are on a different fuse than the headlights though, I believe. We are talking about three different circuits at least:

1. head light lights
2. dash lights
3. head light retractors

Since the retractors don't activate when the lights go out the problem is not common to both circuits even though they both get their activation instructions from somewhere in the headlight switch. And since the dash lights and head lights can go out together or independently it could be something sometimes in common to both.

Some of you may recall I had problems with a stereo in the car staying on. It turned out to be a bad constant feed to the tuner section. I ran a new connections to a known always-on lead and the problem went away. Perhaps the same issue exists (and is spreading!) elsewhere in my electrical system such as in a bulkhead connector or fuse panel.

But, now that I think about it I recall that last summer the nut that holds the headlight switch in the plastic housing in the instrument pod kept vibrating loose (no electrical problems then) until I tightened it down with some needlenose pliers. I'm thinking more and more the headlight switch is the culprit but maybe that's just wishful thinking. At the very least I have a can of that electrical contact cleaner spray I can use to do what I can to clean it up.

Heck, I've rebuilt switches in almost every other car I've owned with good success so there's no reason I can't be optomistic about salvaging this one.
 

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Yah, remember the problem you had with the radio.
If the 3 things are on three different circuits, might try another switch from the junk yard and see what happens. Also might want to look and see if there isn't some relay(s) being used that could also be the culprit.
On your Chevelle the headlights and dash lights are on 2 separate circuits that only share the switch and the connector. Problems that affect both are normally the switch.
If the switch or the area around it glows in the dark...use Elree's idea.
 

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Discussion Starter #12
It's a 1985 model (the first!).

Well, I pulled the headlight switch. Nothing looked obviously wrong. The switch was modestly complicated in that it also incorporated the dash light dimmer rheostat (kind of like a Chevy switch). I was able to get it apart and nothing looked amiss. The contacts inside all looked brand new. I cleaned them up anyway and lightly filed them with a very fine metal file. No improvement. The car at this time permanently had no highbeams but the low beams were working as were the dash lights.

I got done with that portion rather quickly and easily so I decided to dig into the turn signal switch. Again, I found nothing obviously amiss. I got the switch apart and again filed the contacts. The dimmer switch was a really complex litte booger and I had a hard time determining which contact made the low and high beams. I just filed all the contacts to be safe.

I plugged the thing back in fully expecting no improvement but I now had high beams! I happily began to put the thing back together. I had an inspiration to test all the switch functions BEFORE I got it all buttoned back up and found I now didn't have any emergency flashers. I had turn signals, but no flashers. The turnsignal fuse was okay (plus the turns worked) so I dug into the turnsignal/flashers switch to see what I had buggered up. I couldn't get them to work and the switch looked fine. It eventually dawned on me that the hazards should have a separate circuit and fuse than the turns. I couldn't find the fuse! It wasn't in the front trunk and it wasn't under the dash. I checked the fuse panel in the engine compartment (???) and found it there! It was blown.

I must have shorted it when I was testing circuits on the main loom to ground to determine what ran what. Anyway, a quick fuse change and I was back in business. Believe it or not, it was by then after 9pm AND I had a spare 10A fuse on hand!

It's all buttoned up and working fine. I love solving problems like this even if I'm not entirely sure what exactly I did to fix it!
 
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